Asymmetrical Mass in Breast: What Does It Mean?

Asymmetrical Mass in Breast: What Does It Mean?

When one breast differs in shape or size to the other breast, it is referred to as breast asymmetry. In cases such as this, breast cancer screening or a mammogram is recommended. However, when there is an asymmetrical mass in breast spotted during a mammogram, further testing is required. So, what more is there to learn regarding breast asymmetry?

Breast Asymmetry

There is a slight difference in breast shape, position, and size in women’s breasts. In fact, uneven nipples or breasts are not necessarily a medical emergency. However, when there is a slight asymmetrical mass in breast, it is said to be linked to a heightened risk of breast cancer. This is why mammograms are recommended as these tests for changes or abnormalities in the tissues of the breast.

Asymmetrical Mass in Breast and Cancer

Getting a regular mammogram ensures that any abnormalities in the breasts are spotted early. One common abnormality spotted during a mammogram is breast asymmetry, particularly involving breast density as this could be indicative of cancer. Be on the watch as well for changes in the breasts such as the following.

  • Lump under the arm
  • Lump around or in the breast
  • Nipple changes, particularly if it points inward
  • Change in shape or size of a breast
  • Tissue that feels firm or thick under the arm or near the breast
  • Scaly, itchy, or red skin around the breast
  • Puckered or dimpled skin
  • Discharge from the nipple

Causes of Asymmetrical Mass in Breast

The right and left breast develop at a different pace during puberty. However, at any point in an individual’s life, changes in the hormones can affect the growth of one or both breasts. Such changes in hormones occur during or near menopause, during breastfeeding or pregnancy, and at specific points during one’s period.

Hormonal changes can also be associated with the use of contraceptives, like birth control pills. This hormonal contraceptive causes changes in the hormones that result in breasts feeling lumpy. For individuals who experience such symptoms even after discontinuing the use of hormonal contraceptives, it is best to speak with your primary caregiver. Other conditions that affect the shape and size of the breasts include the following.

  • Poland Syndrome: when the muscles in the chest fail to develop properly.
  • Amazia or Amastia: a disorder causing developmental problems in the nipple, areola, and breast tissue.
  • Tubular Breasts: which is also referred to as breast hypoplasia; occurs during puberty.

Overview: Mammogram

An imaging test done particularly for the breasts is called a mammogram. This checks the breasts for the occurrence of abnormalities, such as changes in breast density and the formation of lumps. As mentioned, a mammogram evaluates the densities of both breasts. If there is a difference in breast density, then it is called focal asymmetry or breast asymmetry.

For breast asymmetry that is new, it is referred to as a developing asymmetry. A mammogram that identifies a developing symmetry could likely mean that there is a chance, approximately 12.8 percent, that it would develop into breast cancer. Other causes for a mammogram result showing an asymmetrical breast density are as follows.

  • The presence of a cyst in one breast
  • A normal variation of the composition of fibrous tissue and fats in the breast
  • A large amount of fibrous tissue or fibrosis

Take note, however, that the American Cancer Society claims that cysts or fibrosis do not affect an individual’s risk for getting breast cancer.

Mammogram Results

Breasts are not identical twins, and they are likely to be different in size. However, in terms of structure and density, the breasts are quite similar. So, what happens if a mammogram shows dense asymmetrical breasts? Then it could likely mean that the difference in the density is due to a mass found in the breast, which can then be classified into four categories.

1. Developing Asymmetry

This means that there is a significant change concerning current and past exams. Breast density could have increased, which raises the suspicion of possible malignant cells.

2. Global Asymmetry

When this is the result of the mammogram, it means there is more density or volume in one breast compared to the other. Such a result is normal and is caused by changes in hormones. However, if there is the presence of a mass, then additional imaging tests are required.

3. Focal Asymmetry

In two mammographic views, the images indicate a density, but it is difficult to identify as a true mass. Thus, further evaluation and imaging tests are recommended to rule out abnormal or cancerous masses.

4. Asymmetry

The breasts are evaluated with only one projection, which is not quite reliable since it is one-dimensional. Thus, overlapping structures in the breast can be difficult to spot. So, if an abnormality or lesion is seen, then an additional three-dimensional imaging test is required.

Additional Tests

For mammogram results that indicate asymmetry, additional imaging tests are required. This is to evaluate further if the change in breast density and shape is normal. The primary step is comparing past images of a mammogram for changes in density or shape. For individuals who have never had increased asymmetry or asymmetric breasts, the following tests are requested.

Breast Ultrasound

Such a test helps the doctor diagnose an abnormal finding which was found from the images of an obscure mammogram. Ultrasound of the breast uses sound waves that result in the production of pictures of the internal structures in the breasts. Furthermore, a breast ultrasound helps determine if the mass spotted in the mammogram is a fluid-filled cyst, a cancerous tumor, or if it is benign. In other cases, the mass could be both fluid-filled and solid.

Breast Magnetic Resonance Imaging

An MRI of the breast detects abnormalities of the breast as well as breast cancer. Oftentimes, an MRI is usually done after the biopsy confirms the presence of cancer cells. Moreover, an MRI is recommended for women who are at a heightened risk of breast cancer due to heredity or family history.


When doctors suspect that the abnormality is cancerous or when imaging tests results show an abnormality, then the next step usually involves a biopsy. For this procedure, tissue from the affected breast is taken for testing. If it comes out negative, then regular breast examinations are recommended to monitor any changes. However, if the biopsy comes out as positive, then the doctor will speak to you regarding breast cancer treatment options.

Assymetry and breast cancer

Mom Pamper

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